Rotary sliding-vane compressor

ABSTRACT

A rotary sliding-vane compressor includes an air cylinder, a shaft eccentrically mounted in the air cylinder and rotatable by a motor, sliding vanes coupled to and movable back and forth along radially extending sliding grooves of the shaft, and an oil-gas separating device mounted in the air output port of the air cylinder. The shaft has an axial hole located on one end thereof and coupled to the output shaft of the motor, and two axle bushes respectively mounted on the two opposite ends. Each sliding vane comprises a metal substrate having evenly distributed through holes, and a covering material molded on the surface of the metal substrate and filled up the through holes and having a plurality of discharge grooves.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to compressors and more particularly to a rotary sliding-vane compressor, which has an enhanced structural strength of the shaft, avoiding shaft breaking and increasing the gas output capacity.

(b) Description of the Prior Art

A conventional rotary sliding-vane compressor (see FIG. 9 and FIG. 10) is known to comprise an air cylinder 10, a shaft 20 eccentrically mounted in the air cylinder 10 and having a plurality of radially extending sliding grooves 201, and a plurality of vanes 30 coupled to and reciprocating in the sliding grooves 201. Following rotation of the shaft 20 by a motor 50, the vanes 30 are forced outwards along the sliding grooves 201 subject to the effect of centrifugal force and kept in tight contact with the cylinder wall of the air cylinder 10 by means of an oil membrane so that a series of compression chambers 101 of different volumes is formed in between each two adjacent vanes 30. Thus, air enters the suction hole 102 to mix with the lubrication oil, and, due to increasingly smaller volume of each compression chamber 101, the air and lubrication oil mixture is compressed and forced out of the air output port 103.

In the aforesaid prior art design, the shaft 20 is connected to the output shaft of the motor 50 by a coupling 40. Subject to the constraint of the coupling 40, the diameter of the shaft 20 is limited, and therefore the depth of the sliding grooves 201 is limited. In consequence, the length of the vanes 30 and the maximum volume of each compression chamber 101 are limited. When wishing to increase the gas output, the size of the air cylinder 10, the shaft 20 and the sliding vanes 30 must be relatively increased. In that case, the total dimension of the air compressor will be greatly increased.

Further, during a high speed operation of the aforesaid conventional rotary sliding-vane compressor, the air cylinder 10 will generate much waste heat due to friction. Therefore, it is necessary to spray a proper amount of lubricating oil into the inside of the air cylinder 10 to prevent overheat. Thus, output gas will contain tiny droplets of oil or other impurities. To avoid interference of compressed gas mass with normal functioning of the air compressor, an oil-gas separating device 60 is normally used and installed in the gas output port of the air cylinder 10. The oil-gas separating device 60 has installed therein an air filter element to remove droplets of oil and other impurities from the gas passing therethrough. Because the air filter element directly faces a hot compressed oil-saturated gas during operation of the oil-gas separating device 60, it wears quickly with use. Further, the sliding vanes 30 will deform soon when working under a high temperature environment, causing lateral leakage and further resulting in gas output reduction and energy waste. Even worse, the sliding vanes 30 may be stuck in the sliding grooves 201 of the shaft 20.

Therefore, it is desirable to provide a rotary sliding-vane compressor which eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. The rotary sliding-vane compressor of the present invention comprises an air cylinder, a shaft eccentrically mounted in the air cylinder and rotatable by a motor, sliding vanes coupled to and movable back and forth along radially extending sliding grooves of the shaft, and an oil-gas separating device mounted in the air output port of the air cylinder, wherein the shaft has an axial hole located on one end thereof and directly coupled to the output shaft of the motor for enabling the shaft to be rotated with the output shaft of the motor synchronously. As the axial hole of the shaft is directly coupled to the output shaft of the motor without using any coupling means, energy loss is minimized during transfer of the rotary driving force from the motor to the machine head. This arrangement allows the two opposite ends of the shaft to be maximized, thus the depth of the sliding grooves can be maximized to accommodate the sliding vanes that have a relatively greater size when compared to the equivalent prior art design for high gas output.

Further, each sliding vane comprises a metal substrate having evenly distributed through holes, and a covering material molded on the surface of the metal substrate and filled up the through holes. Further, the covering material has a plurality of discharge grooves located on at least one of two opposite sides thereof. Thus, the sliding vanes have a high structural strength and high precision in size to achieve best performance without causing any damage to the air cylinder. Under an accurate control of the thermal expansion coefficient, the air cylinder and the shaft work synchronously to compress air. Therefore, the invention has high precision and low cost characteristics and avoids a secondary processing process.

Further, a cyclone type oil-gas separating device is mounted in the air output port of the air cylinder to remove oil particles from the compressed gas passing through the air output port. When hot compressed oil-saturated gas goes out of the gas output port of the air cylinder into the oil-gas separating device, it flows along an annular gas passage at a high speed to induce a centrifugal force that causes relatively greater oil particles to be forced away from the gas flow to the outside of the oil-gas separating device, allowing the gas flow containing relatively smaller oil particles to be further filtered by an air filter element in the oil-gas separating device. Thus, the lifespan of the air filter element can be greatly extended, reducing material consumption and maintenance cost.

Further, the shaft has a keyway in the axial hole thereof for engagement with a key at the output shaft of the motor for allowing synchronous rotation of the shaft with the output shaft of the motor, minimizing energy loss during transfer of the rotary driving force from the motor to the machine head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rotary sliding-vane compressor in accordance with the present invention.

FIG. 2 is an exploded view of a part of the rotary sliding-vane compressor in accordance with the present invention, illustrating the structure of the air cylinder, the shaft and the sliding vanes.

FIG. 3 is a schematic sectional assembly view of a part of the rotary sliding-vane compressor in accordance with the present invention, illustrating the shaft positioned in the air cylinder and coupled to the motor.

FIG. 4 is a cutaway view of one sliding vane in accordance with the present invention.

FIG. 5 is a sectional view of one sliding vane in accordance with the present invention.

FIG. 6 is a sectional view of a part of the present invention, illustrating movement of the sliding vanes relative to the shaft during rotation of the shaft in the air cylinder.

FIG. 7 is a schematic sectional view of a part of the present invention, illustrating the arrangement of the oil-gas separating device in the air cylinder.

FIG. 8 is a schematic sectional elevation of the oil-gas separating device in accordance with the present invention.

FIG. 9 illustrates the structural arrangement of a rotary sliding-vane compressor according to the prior art.

FIG. 10 is a sectional view of a part of the rotary sliding-vane compressor according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1 and FIG. 2, a rotary sliding-vane compressor in accordance with the present invention comprises an air cylinder 1, a shaft 2 eccentrically mounted in the air cylinder 1 and having a plurality of radially extending sliding grooves 21, a plurality of sliding vanes 3 coupled to and movable back and forth along the sliding grooves 21, and an oil-gas separating device 4 mounted in the air output port (not shown) of the air cylinder 1. The shaft 2 has its two distal ends respectively pivotally coupled to a front cap 11 and a rear cap 12 at the front and rear sides of the air cylinder 1 and respectively capped with a front end cap 111 and a rear end cap 121.

The main features of the present invention are outlined hereinafter. The shaft 2, as shown in FIG. 2 and FIG. 3, is rotatably mounted in the air cylinder 1, having an axial hole 22 on its one end for coupling to a motor 5 and a keyway 221 in the axial hole 22 for engagement with a key (not shown) at the output shaft 51 of the motor 5. By means of the axial hole 22 and the keyway 221, the shaft 2 is coupled to the output shaft 51 of the motor 5 (see FIG. 3). Thus, the diameter of the two opposite ends of the shaft 2 is relatively greater than the prior art design, and the sliding grooves 21 can be made relatively deeper than the sliding grooves 201 of the shaft 20 of the prior art design. Further, two axle bushes 23 are respectively mounted on the two opposite ends of the shaft 2 in the front cap 11 and the rear cap 12, ensuring smooth rotation of the shaft 20 in the air cylinder 1. The axle bushes 23 are made of a wear resistant material (aluminum oxide, zirconium oxide or Babbitt alloy) that is capable of supporting smooth rotation of the shaft 2 in the front cap 11 and the rear cap 12 and can bear friction heat produced during rotation of the shaft 2.

The sliding vanes 3 are rigid plate members fitting the sliding grooves 21 in width, each comprising a metal substrate 31 that works as a support (see FIG. 4 and FIG. 5) and a covering material 32 is a compound plastic material directly molded on the surface of the metal substrate 31 by insert molding. The metal substrate 31 has evenly distributed through holes 311. During insert molding, the covering material 32 fills up the through holes 311, enhancing the bonding tightness between the metal substrate 31 and the covering material 32, and a plurality of discharge grooves 321 are formed on at least one of the two opposite sides of the covering material 32. These discharge grooves 321 work as lubrication channels and pressure channels during floating of the sliding vanes 3 in the sliding grooves 21.

By means of the aforesaid arrangement, the axial hole 22 and keyway 221 of the shaft 2 can be directly coupled to the output shaft 51 of the motor 5 without using any coupling means, minimizing energy loss during transfer of the rotary driving force from the motor 5 to the machine head. As the diameter of the two opposite ends of the shaft 2 is maximized, the depth of the sliding grooves 21 can be maximized to accommodate the sliding vanes 3 that have a relatively greater size when compared to the equivalent prior art design (see FIG. 9) for high gas output.

Further, the oil-gas separating device 4, as shown in FIG. 7 and FIG. 8, comprises a cylindrical housing 41 having an air inlet 411 and an air outlet 412, an air filter element 42 mounted in the cylindrical housing 41 and connected between the air inlet 411 and the air outlet 412, a partition board 43 mounted in the cylindrical housing 41 to divide the internal space of the cylindrical housing 41 into a flow-guide chamber 44 and a filter chamber 45, and an annular baffle plate 46, a guide tube 47 and an oil drain hole 48 mounted in the flow-guide chamber 44. The filter chamber 45 accommodates the air filter element 42, keeping the air filter element 42 in communication between the air inlet 411 and the air outlet 412. The annular baffle plate 46 has its one end tightly connected with the partition board 43 and its other end spaced from the cylindrical housing 41 at a distance, and therefore an annular gas passage 441 is defined between the outside wall of the annular baffle plate 46 and the inside wall of the cylindrical housing 41. The guide tube 47 is connected between the air inlet 411 and the annular gas passage 441. The partition board 43 has an air vent 431 disposed in the inside of the annular baffle plate 46 in communication with the inside space of the air filter element 42 in the filter chamber 45.

When hot compressed oil-saturated gas goes out of the gas output port of the air cylinder 1 through the guide tube 47 into the oil-gas separating device 4, it flows along the annular gas passage 441 at a high speed to induce a centrifugal force that causes relatively greater oil particles to be forced away from the gas flow to the outside of the flow guide chamber 44 through the oil drain hole 48. The gas flow containing relatively smaller oil particles is forced by the following gas flow that continuously flows into the annular gas passage 441 to pass over the annular baffle plate 46 into the air filter element 42 in the filter chamber 45 through the air vent 431 where the air filter element 42 removes the residual oil particles to a level below 1 ppm. Thus, the lifespan of the air filter element 42 can be greatly extended, reducing material consumption and maintenance cost.

As shown in FIG. 3 and FIG. 6, the sliding vanes 3 are respectively coupled to the sliding grooves 21 of the shaft 2, and movable back and forth along the sliding grooves 21. Following rotation of the shaft 2 by a motor 5, the sliding vanes 3 are forced outwards along the sliding grooves 21 subject to the effect of the induced centrifugal force and kept in tight contact with the cylinder wall of the air cylinder 1 so that a series of compression chambers 13 of different volumes is formed in between each two adjacent vanes sliding vanes 3. Thus, intake air can mix with the applied lubrication oil thoroughly, and, following reducing in volume of each compression chamber 13, the air and lubrication oil mixture is compressed and forced out of the air cylinder 1. In order to prevent overheat or jam of the sliding vanes 3 in the sliding grooves 21 of the shaft 2 due to axial displacement of the shaft 2 during its rotation in the air cylinder 1, the invention uses the wear resistant axle bushes 23 to support smooth rotation of the shaft 2 in the front cap 11 and the rear cap 12 and to bear friction heat produced during rotation of the shaft 2.

Further, because the sliding vanes 3 are made by means of insert molding, they have a high structural strength and high precision in size to achieve best performance without causing any damage to the air cylinder 1. Under an accurate control of the thermal expansion coefficient, the air cylinder 1 and the shaft 2 work synchronously to compress air. Therefore, the invention has high precision and low cost characteristics and avoids a secondary processing process.

Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A rotary sliding-vane compressor, comprising an air cylinder, a cylinder shaft eccentrically mounted in said air cylinder, said cylinder shaft comprising a plurality of radially extending sliding grooves, a plurality of sliding vanes coupled to and movable back and forth along said sliding grooves, and a motor having an output shaft adapted for rotating said shaft wherein: said cylinder shaft comprises a first end, a second end opposite to said first end, an axial hole located on said first end and coupled to said output shaft of said motor for enabling said cylinder shaft to be rotated synchronously with said output shaft of said motor, two axle bushes respectively mounted on said first end and said second end; each said sliding vane comprises a metal substrate having evenly distributed through holes, and a covering material molded on the surface of said metal substrate and filled up said through holes, said covering material having a plurality of discharge grooves located on at least one of two opposite sides thereof.
 2. The rotary sliding-vane compressor as claimed in claim 1, wherein said air cylinder comprises a front cap and a rear cap respectively located on two opposite ends thereof; said cylinder shaft has the first end and second end thereof respectively pivotally connected to said front cap and said rear cap.
 3. The rotary sliding-vane compressor as claimed in claim 1, wherein said cylinder shaft further comprises a keyway disposed inside said axial hole and coupled to a part of said output shaft of said motor to prohibit rotation of said cylinder shaft relative to said output shaft of said motor.
 4. The rotary sliding-vane compressor as claimed in claim 1, wherein the covering material of each said sliding vane is a compound plastic material molded on the associated metal substrate by insert molding.
 5. The rotary sliding-vane compressor as claimed in claim 1, wherein said air cylinder comprises an air output port and an oil-gas separating device mounted in said air output port.
 6. The rotary sliding-vane compressor as claimed in claim 5, wherein said oil-gas separating device comprises a housing having an air inlet and an air outlet; an air filter element mounted in said housing and connected between said air inlet and said air outlet of said housing; a partition board mounted in said housing to divide the internal space of said housing into a flow-guide chamber and a filter chamber, and an annular baffle plate, a guide tube and an oil drain hole mounted in said flow-guide chamber, said filter chamber accommodating said air filter element, said annular baffle plate having one end thereof tightly connected with said partition board and an opposite end thereof spaced from said housing at a distance so that an annular gas passage is defined between said annular baffle plate and said housing, said guide tube being connected between said air inlet and said annular gas passage, said partition board having an air vent disposed in the inside of said annular baffle plate in communication with the inside space of said air filter element. 